1. Field of the Invention
The present disclosure relates to a prepreg, a metal-clad laminated plate formed by using the prepreg, and a printed wiring board formed by using the metal-clad laminated plate.
2. Description of the Related Art
Conventionally, a prepreg is formed by impregnating a woven fabric base material with a resin composition containing a thermosetting resin, and then heating and drying the woven fabric base material until the resin composition comes into a semi-cured state (see, for example, Unexamined Japanese Patent Publication No. 2006-137942, Unexamined Japanese Patent Publication No. 2007-138152 and Unexamined Japanese Patent Publication No. 2008-007756). A metal-clad laminated plate can be produced by laminating a metal foil on the thus formed prepreg. Further, a printed wiring board can be produced by forming a conductive pattern to the metal-clad laminated plate. Thereafter, a semiconductor element is mounted on the printed wiring board, and sealed to produce a package.
Packages that have been commonly used in smart phones and tablet PCs in recent years include PoP (Package on Package). In the PoP, a plurality of sub-packages are laminated, and therefore mountability of sub-packages and electrical conduction reliability for each sub-package are important. The mountability and conduction reliability are improved by decreasing the absolute value of warpage of a package (including sub-packages) at room temperature. The mountability and conduction reliability are improved by decreasing the amount of change in warpage of a package when the ambient temperature is changed from room temperature to 260° C. Accordingly, development of a substrate material which ensures a reduction in warpage of a package is extensively conducted.